The now-extinct Titanoboa, seen in an artist's rendering, is the largest known snake. One expert says it likely lived part of the time in the water and would have killed its prey by squeezing it.
Jason Bourque
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Jason Bourque

The now-extinct Titanoboa, seen in an artist's rendering, is the largest known snake. One expert says it likely lived part of the time in the water and would have killed its prey by squeezing it.

A vertabra from the Titanoboa dwarfs that of an adult Green anaconda. Cold-blooded animals such as snakes require warm climates to grow large. The Titanoboa's size suggests that the average temperature once was considerably higher than it is now.
Kenneth Krysko
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Kenneth Krysko

A vertabra from the Titanoboa dwarfs that of an adult Green anaconda. Cold-blooded animals such as snakes require warm climates to grow large. The Titanoboa's size suggests that the average temperature once was considerably higher than it is now.

A live python crawls over the enormous vertebra of Titanoboa.
Jason Head
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Jason Head

A live python crawls over the enormous vertebra of Titanoboa.

Jason Head

The largest known snake that ever lived grew as long as a school bus, was 3 feet thick, weighed over a ton and ate crocodiles — presumably whole and al dente.

Not to worry: Titanoboa cerrejonensis lived 60 million years ago and is extinct. But for some 20 million years after the dinosaurs disappeared, this 42-foot serpent ruled the land.

Scientists discovered enormous vertebrae from a Titanoboa in a coal mine in Colombia. The spinal column bones were 5 inches across, more than twice the size of the biggest South American boa constrictor or anaconda.

"I just about jumped out of my chair," says paleontologist Jason Head of the University of Toronto, recalling the moment he first saw one of the bones. He said he couldn't help but laugh "because it was so ridiculously big. I said I know this is the world's largest snake."

Head, who specializes in the fossils of giant reptiles, says the snake probably lived part of the time in the water, like present-day anacondas. It was the largest vertebrate on land after the dinosaurs disappeared and probably would have killed its prey by squeezing them.

In this week's issue of the journal Nature, Head points out that a cold-blooded animal that big would have had to live in a very hot place to survive. According to his calculations, the average temperature would have been about 90 degrees. That's several degrees warmer than the present-day tropical average and is warmer than scientists believed the tropics ever got, even during ancient periods of greenhouse warming.

Conventional wisdom holds that during global warming events, the tropics don't heat up as much as polar or temperate regions, according to climate scientist Matthew Huber of Purdue University. He says that if Head is right about Titanoboa's toasty climate, "that's in some sense bad news for us for the future.

"It says there's no magical thermostat that keeps the tropics at a reasonable temperature, that they will warm, too, in a global warming world," Huber notes.

At the same time, he says, it also suggests that if the tropics do warm up a lot during warming events, they can survive those higher temperatures — at least well enough to provide a habitat for giant serpents.

Correction Feb. 6, 2009

The introduction to the audio version of this story said that the snake's vertebrae were found "in the rainforests of Colombia." In fact, the area where the bones were found is no longer a rainforest, although it was when the snake was alive, millions of years ago.